Exhaust gas turbochargers are used to boost the output of internal combustion engines. In modern internal combustion engines, matching the exhaust gas turbocharger to variable operating conditions is becoming increasingly more difficult. So-called variable turbine and/or compressor geometry offers one popular possibility. In a variable turbine geometry the guide vanes of the guide apparatus are aligned more or less steeply to the flow upstream of the turbine wheel according to the turbine power demand. In variable compressor geometry the diffusor vanes are aligned more or less steeply to the flow downstream from the compressor wheel. The vanes are generally adjusted via so-called adjusting levers which are moved by an adjusting ring located concentrically to the axis of the exhaust gas turbocharger. For radial turbines or radial compressors the guide vane or diffusor vane is generally parallel to the shaft axis. The shaft of the guide vane or diffusor vane is preferably supported twice in a housing and is turned by means of an adjusting lever which acts on the vane shaft between the two bearing points. If the adjusting lever is to be moved directly by means of recesses in the adjusting ring, its end, as described for example in EP 1 520 959, must be made cylindrical so that it does not stick in the groove.
Even if the adjusting ring is provided with lifters which engage the corresponding grooves of the adjusting lever, these lifters must be made cylindrical, for example as inserted driving pins, as shown by EP 1 234 951.
To adjust the guide vanes the adjusting ring is turned concentrically around the turbocharger axis, by which the guide vanes are pivoted by means of the adjusting levers.
Due to this rotary and pivoting motion, the cylinder of the adjusting lever or of the grooved ring is moved on the groove surface of the grooved ring or of the adjusting lever. Due to the linear support of the cylinder in the grooves of the adjusting lever or grooved ring, very high Hertzian compressive loads arise in spite of moderate normal forces. The sliding partners wear in operation due to the relative movements of the cylinder on the groove surface and the high compressive loads per unit area
U.S. Pat. No. 4,741,666 discloses a device for transmitting an adjustment force from an adjusting ring to the vane shaft of a pivotally mounted guide vane, with an adjusting lever and a driving sleeve which can be connected to an adjusting ring and which is pivotally mounted on a pin. The driving sleeve and a groove of the adjusting lever each have contact surfaces which are matched in pairs to one another.
Comparable devices are disclosed in EP 1 396 621 and U.S. Pat. No. 6,312,217.